Method of and apparatus for dealing with floating sludge in digestion chambers for sewage treatment



Nov. 6, 1928. 1,690,682

K. IMHOFF ET AL METHOD OF AND APPARATUS FOR DEALING WITH FLOATING SLUDGEIN DIGESTION CHAMBERS FOR SEWAGE TREATMENT Filed Aug.-25, 1924 PatentedN... e, 1928.

g UNITED STATES PATENT Q Fl'cE.

1mm. mnorn nn rnmz rams, or Essen, (1mm.

1 U i r a METHOD AND APPARATUS FOR DEALING WITH FMATIN G SLUDGE INDIGESTION CHAMBERS FOB SEWAGE TREATMENT.

Application filed August 25, 1924, Serial no. 734,009, and in German 1.,7, 1924.

o The floating sludge formed in the digestion" chambers of sewagetreatment plants, for'instance of Imhoff tanks, acts detrimentally uponthe proper working of said plants.

I Floating sludge exposed for some time to the atmosphere at the watersurface, soon-harde'ns so that it cannot be discharged through pipes butmust be. removed manuallysor by chanical means which adds to the cost ofdis posal. L The formation of hard floating sludge can be completelyavoided by inserting in the digestion chamber below water level a coverso as to keep the floatingslu'dge completely and continuously submergedin order that it does not come in contact with the atmosphere. The

" floating sludge remainsin a liquid condition and easily settles to thebottom of the digess tion chamber, or, if it remains in suspension itcan be let-.ofi or pumped-ofl'below water level.

The cover for keeping the sludge sub-' merged must be gas-permeable sothat it; allowsfa passage therethrough of the gas ascending from thedigestionchamber in small bubbles while completely preventing sludgepassing ther'ethrough.

The accompanying drawing illustrates an Imhofi' tank fitted with theimproved arrangement: Fig. 1 is a sectional plan view of .3 the same,Fig; 21s a perpendicular section through the same in connection withagas collector, and Figs. 3 and .3 'show a preferred form of the coverin a sectional side view and, in a plan view respectively. The Imhofl'tank comprisesta settlinfg basin a and a digestion chamber 6, the;oating I sludge collecting'in the upper part of the' latter on the rightand left from said settling basin.- At the top of the digestion chamber6, a separate water'chamber m isilo cated, at the bottom of whichand'thus below the water level therein acover z" is'located', 1, thatserves to keep the floating sludge in the digestion chamber 'com lete ysubmerged. The gas-permeable part 0 said cover need not extend over thewhole surface of the di estion chamber but, for instance, the inclineparts 9% of said cover, which is' thus rqof-shaped, ma be gastight anddesigned to lead the gases t to t e gas-permeable top part of the cover2'.

Tolet-off from time to time the floating sludge collected, lateralflag-controlled outlets 1 k of "known m. are provi edi'n the walls ofthe digestion chamber below water' level. 4 "Theike'eping of thefloating sludge at a me-f in" said water; .chamber.

' tom of andfthus water chamber, and flap-controlled outlets a certaindistance below water level oifers spec'lal advantages for a utilizationof the gases from the digestion chamber because the presence of floatingsludge in the gas bells c, which 1s thereby effectively prevented, wouldbe ar-' ticularl detrimental; the gases gaine in said be lsbeing ledthrough pipes (1 into a gas collector e.

The cover 9' can be made of porous mate.- rial, for instance of wood,filter slabs,or coarse concrete. For cleaning the'sarnefrom time totime, it is recommendableto make it hol- Y low for forcing therethroughgas or water, for which purpose the gas from the collector e can be usedand led by means of a fan g through pipes f into the cover 11.

A articularly simple gas-permeable cover 7 which can also be easilyremoved, is fprmed of a wooden frame that is panelled with a series ofnarrow poplar-wood strips having a keynd-groove connection. 7 Thepoplarwoo is porous and permits for some time an easy passage of gases'therethrough. If the porosity diminishes, the fine slots between thesingle strips suflice for a passage of the gases therethrough. (Figs.3'1") What we claim, is i 1. A method of dealing with floating sludge indigestion chambers for sew'a' e treatment, consisting. in intentionallycovering the floating sludge below the water level in the digestionchamber thereby kee ing the same con-- tinuouslg submerged unt' itsbeing eventually let o and allowing the gases ascending. from thedigestion chamber to escape to the water level directly through-saidcovering, substantially as set forth. 5 Y 2. A device for dealing withfloating sludge, in digestion chambers forsewage treatment, comprising aseparate chamber at the top of the atter, and a gas-permeable coverlocated at the bottom of and thus below the water level 3. A device fordealing with floating sludge indigestion chambers forsewage treatment,as s in t e walls of the-digestion chamber below said cover,

4. A device fordeal' in digestion chambers or. sewage treatmentcomprising a separate water chamber at the as; floating sludge top ofthe latter, a roof+shaped coverhaving a gas-permeable to y bel w thewater level in said part located at, the bot cified in claim 2,flap-controlled outlets in the walls of the digestion chamber below saidcover. Y g

5. A device for dealing with floating sludge in digestion chambers forsewage treatment,-

comprising a separate water chamber at the top of the latter, agas-permeable cover lo cated at the bottom of and thus below the waterlevel in said water Chamber and consisting of awooden frame panelledwith a series 0t narrow iyoplar-wood-lstrips having -a key- 10and-groove connection, and flap-controlled outlets in the walls of thedigestion chan ber below said cover.

. .j In testimony whereof we have hei eunto set

